August 17, 2006

Plate size influences portion size

NEW YORK (Reuters Health) - Want to lose weight? Try eating
off smaller plates. A new study shows that using smaller bowls
and spoons may curb the amount of food eaten.

"People could try using the size of their bowls and
possibly serving spoons to help them better control how much
they consume," write researchers in the American Journal of
Preventive Medicine.

"Those interested in losing weight should use smaller bowls
and spoons, while those needing to gain weight -- such as the
undernourished or aged -- could be encouraged to use larger
ones," add Dr. Brian Wansink, of Cornell University, and
colleagues.

In a prior study, researchers found that teenagers poured
77 percent less juice into tall narrow glasses than they did
into short wide glasses. Similarly, in another study,
Philadelphia bartenders were found to pour less liquor into
"highball" glasses than they did into tumblers. These studies
suggest that individuals may adjust their serving portions
depending on the size of their bowls or spoons.

To investigate, Wansink and his team conducted a study of
85 nutrition experts, including faculty, staff, and graduate
students, from a large midwestern university, who attended an
ice cream social. They were randomly given a 17 ounce or 34
ounce bowl along with a 2 ounce or 3 ounce ice cream scoop and
allowed to serve themselves ice cream.

Afterwards, their ice cream was weighed while they
completed a short survey about how much ice cream they thought
they had served themselves and how the size of their bowl and
spoon differed from what they normally used.

Study participants who received the larger bowls
unknowingly served themselves 31 percent more ice cream than
did those with smaller bowls. Ice cream servings also increased
by 14.5 percent among those with larger serving spoons,
regardless of the size of the bowl. And nearly all of the
adults (82 of 85) ate all of their ice cream.

Altogether, those with large bowls and large serving spoons
served themselves -- and ate -- nearly 57 percent more ice
cream than those with smaller bowls and spoons, the team
reports.

"What is critical to note, however, is that people -- even
these nutrition experts -- are generally unaware of having
served themselves more," write the authors.

"The fact that even they end up being tripped up by these
cues just helps to show how ubiquitous and how subversive these
illusions can be," Wansink said in a statement.

Based on the findings, "obese patients may want to use
smaller bowls and spoons at home to reduce over-consumption,"
according to Wansink and his colleagues.

Among undernourished individuals, on the other hand,
"larger bowls and spoons would encourage more food intake than
the smaller bowls and spoons that are often provided," they
conclude.